9:20 AM PT -- Brown just spoke at a team meeting and issued an "emotional apology" to the Raiders ... ESPN's Josina Anderson reports.

Anderson adds Oakland's team captains stood alongside the receiver.

Antonio Brown hurled a racial slur at Oakland Raiders general manager Mike Mayock during their heated altercation this week -- calling him a "cracker" -- so says ESPN.

ESPN's Josina Anderson says multiple sources confirm Brown "unleashed a barrage of cuss words during the altercation" ... including using the word "cracker," a derogatory term for white people.

Anderson reports Mayock "tried to keep his cool during the situation" and tried to walk away as he saw things starting to escalate.

The news comes in the wake of NFL Network's Ian Rapoport reporting that Brown threatened to punch Mayock in the face during the altercation that started over Mayock's decision to fine AB roughly $54k for missing workouts.

The Raiders are currently weighing their options with Brown and could cut him before their season opener on Monday Night Football -- which would be a HUGE move considering they just signed him to a 3-year, $50 million contract this offseason.

Brown's agent, Drew Rosenhaus, says he's working like a maniac trying to salvage the relationship ... but most people believe Brown is done in Oakland.